/Engine/Plugins/Online/OnlineFramework/Source/Party/Public/SocialManager.h
Validate that we are clear to try joining a party of the given type. If not, gives the reason why.
virtual [FJoinPartyResult](API\Plugins\Party\Party\FJoinPartyResult) ValidateJoinAttempt ( const [FOnlinePartyTypeId](API\Plugins\OnlineSubsystem\FOnlinePartyTypeId) & PartyTypeId ) const